1. Field of the Invention
The present invention relates to a multi-window display apparatus for displaying a plurality of image information on a display device of a work station by using windows.
2. Description of the Background Art
One of the important features of a work station is a multi-window display function in which a plurality of windows are manipulated on a display screen in various modes such as moving, enlarging, contracting, and superposing.
An example of a conventional multi-window display apparatus is shown in FIG. 1.
In this apparatus, a graphics controller 101 of the bit block transfer type reads out a bit map from a bit map memory 102, which is a memory for the display which stores bit values of picture elements in one or more bits. The graphics controller 101 then sends the bit map to a frame buffer 103, through which an image given by the values of the picture elements stored in the bit map memory 102 is displayed on a CRT 104. The graphics controller 101 is also connected with a host CPU 106, a main memory device 107, an external memory device 108, a mouse 109, and a keyboard 110 of a work station, through a host bus 105, from which various commands related to the display can be given.
In such a conventional multi-window display apparatus, only rectangular windows are used exclusively, and a user is not provided with choices for the form of the windows, although the size of the windows and the size of letters in the windows can be changed freely. The rectangular windows are also used exclusively in displaying graphic images, regardless of the content of the graphic images to be displayed.
Thus, the conventional multi-window display apparatus has been rather limited in terms of manipulations of windows. For example, it has been impossible to construct a window in such a form from which a content displayed in the window can be easily recognized, or to selectively deal with a part of the window display such as a head portion of a display in a shape of a human body.